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10-03-2008, 09:51 PM   #16
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QuoteOriginally posted by audiobomber Quote
I does have A-mount contacts. I can set the aperture electronically and it meters automatically. It just won't open up to F2.8 in auto mode. I'm 90% certain it's a little misalignment that causes the electronic aperture control to cycle from f4-f32 instead of f2.8-f28.

Anyway, I have manual control of the aperture and auto metering, and that's all I require.
Sounds good. I saw your original picture of the mount before you posted your reply and edited my post to reflect the dual nature of the mount. Apparently the mount was originally designed for a slower lens.

Have fun!

Steve

10-03-2008, 10:39 PM   #17
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QuoteOriginally posted by stevebrot Quote
Sounds good. I saw your original picture of the mount before you posted your reply and edited my post to reflect the dual nature of the mount. Apparently the mount was originally designed for a slower lens.

Have fun!

Steve
I should have been more clear. The two photos of lenses that I posted today were not photos of my lens. I found them on the net and posted them just to illustrate what I had done with the extra pin and flange.
10-04-2008, 09:05 AM   #18
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QuoteOriginally posted by audiobomber Quote
I should have been more clear. The two photos of lenses that I posted today were not photos of my lens. I found them on the net and posted them just to illustrate what I had done with the extra pin and flange.
I meant this picture that you posted on another thread that shows both the Ricoh pin and what are possibly A-mount contacts...

10-04-2008, 10:21 AM   #19
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QuoteOriginally posted by stevebrot Quote
I meant this picture that you posted on another thread that shows both the Ricoh pin and what are possibly A-mount contacts...

That's not my lens either, but it's the same pin configuration and yes, it has A contacts.

10-05-2008, 01:37 AM   #20
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If you look at the Mark Roberts site, you can see that the contacts on the lens are detected as 0 1 1 * 1 0 for F2.8 lenses and 0 0 1 * 1 0 for F4.0 lenses. It looks like the second contact from the left is not being detected and that is making the camera think it is an F4.0 lens instead of an F2.8 lens. The funny thing is that your mount looks to be coded 000*10 which would decode as an F4.5 to F32 lens.

Last edited by pentaxman; 10-05-2008 at 01:46 AM.
10-07-2008, 11:23 PM   #21
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QuoteOriginally posted by audiobomber Quote
I bought a 28mm F2.8 lens on eBay. I hadn't heard of the mismatches in mounts before and I stupidly bought a lens with the super large flange in the mount and the pin that jams on some cameras. Even more stupidly, I did the surgery instead of returning it. I cut the flange and removed the pin so that it won't jam. Now I find that the shutter can't open to F2.8, it only goes to 4.0. Is it because I didn't remove enough of the flange, or is there another problem?
I did the flange excess removal on three different lens and I have not run into metering problem. You an take a look at my grinding operation with Vivitar 28mm f/2.5 from Kiron. A slow grinding drill is recommended to me from others, but I used something fast with precaution on protecting the rear element. The flange only protects the aperture control and it should not affect the metering.

Vivitar 28mm f/2.5 from Kiron -- Hin's Tech Corner

This is an interesting thread.

Last edited by hinman; 10-08-2008 at 01:22 AM.
10-08-2008, 05:37 AM   #22
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QuoteOriginally posted by pentaxman Quote
If you look at the Mark Roberts site, you can see that the contacts on the lens are detected as 0 1 1 * 1 0 for F2.8 lenses and 0 0 1 * 1 0 for F4.0 lenses. It looks like the second contact from the left is not being detected and that is making the camera think it is an F4.0 lens instead of an F2.8 lens. The funny thing is that your mount looks to be coded 000*10 which would decode as an F4.5 to F32 lens.
That's not my mount, I found the image on the net and used it as an example of what my mount looks like. I did this to save time instead of photographing my lens, downsizing in Picasa and loading to ImageShack, which is my only system for web display and takes a lot of time. About as much time as I've spent explaining that the lens images I posted were not my lens.

Thanks Pentaxman. I will check out your very concise directions. I had F2.8 again for a little while then lost it, so your explanation of the pin losing contact seems quite possible.

Last edited by audiobomber; 10-08-2008 at 05:59 AM.
10-08-2008, 05:48 AM   #23
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QuoteOriginally posted by hinman Quote
I did the flange excess removal on three different lens and I have not run into metering problem. You an take a look at my grinding operation with Vivitar 28mm f/2.5 from Kiron. A slow grinding drill is recommended to me from others, but I used something fast with precaution on protecting the rear element.
I had run across your site while looking for a solution to the flange. I ended up using a hacksaw blade and it did a pretty smooth job without a lot of effort.

QuoteOriginally posted by hinman Quote
The flange only protects the aperture control and it should not affect the metering.
Thanks, good to know.

Here are some samples from my lens if anyone cares to comment. I was a little disappointed with the bokeh in the very high contrast shots of the berries and crabapple, but other than that it looks nicely detailed, nice colour and quite acceptable distortion levels.

Picasa Web Albums - Dan - 28mm A lens

10-24-2008, 03:56 PM   #24
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QuoteOriginally posted by pentaxman Quote
If you look at the Mark Roberts site, you can see that the contacts on the lens are detected as 0 1 1 * 1 0 for F2.8 lenses and 0 0 1 * 1 0 for F4.0 lenses. It looks like the second contact from the left is not being detected and that is making the camera think it is an F4.0 lens instead of an F2.8 lens.
You nailed this Pentaxman. The reason my lens won't go to 2.8 is because one of the pins is completely missing. It must have dropped out when I had it apart. Now I have to figure out where to get a replacement. Any ideas?

Last edited by audiobomber; 10-24-2008 at 10:49 PM.
10-24-2008, 06:12 PM   #25
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QuoteOriginally posted by audiobomber Quote
You nailed this Pentaxman. The reason my lens won't go to 2.8 is because one of the pins is completely missing. It must have dropped out when I had it apart. Now all I have to figure out where to get a replacement. Any ideas?
Any metal (a pin, aluminum foil, etc.) that covers/seals/fills up that hole will do the job.
10-24-2008, 06:14 PM   #26
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If you can find a dead A lens, you can take off one pin from the rear mount and put it into your lens.
10-24-2008, 10:51 PM   #27
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QuoteOriginally posted by ddhytz Quote
Any metal (a pin, aluminum foil, etc.) that covers/seals/fills up that hole will do the job.
Nice idea. Worth a try. I especially like the aluminum foil. Thanks dd.
10-26-2008, 08:52 PM   #28
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QuoteOriginally posted by ddhytz Quote
Any metal (a pin, aluminum foil, etc.) that covers/seals/fills up that hole will do the job.
Whoot! I stuffed some aluminum foil in the pinless hole, and I now have a properly functioning f/2.8 lens. Great tip, thanks.
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